1. Field of Invention
The present invention relates to a DC/AC adapter assembly, and more particularly to a DC/AC adapter assembly with a power-overload protection circuit.
2. Description of the Related Art
Power sources of an automobile include an automotive battery and a cigarette lighter outlet. In the past, a cigarette lighter was provided in an automobile for drivers and passengers who are smokers. More recently, smokers have avoided smoking in cars for health and safety reasons. Although the cigarette lighter is not often used to light cigarettes, a cigarette lighter outlet in the automobile is often used to provide electricity to an electrical appliance such as a laptop, a personal digital assistant (PDA), a mobile phone, or the like.
FIGS. 6 and 7 illustrate a conventional DC/AC adapter assembly 54 having a DC/AC adapter 40 and a cable 50. The DC/AC adapter 40 is configured to receive input DC electricity, which may have 150-watts or 200-watts of electrical power, through the cable 50. The DC/AC adapter 40 has an enclosure 42, a circuit board (not shown) and a socket 41. The circuit board is mounted in the DC/AC adapter 40 for transforming the input DC electricity to AC electricity (110V/220V). The socket 41 is mounted in a side 43 of the enclosure 42 and has a contact (not shown). The contact is mounted in the socket 41 and is connected with the circuit board.
The cable 50 is used to connect the DC/AC adapter 40 with a cigarette lighter outlet of an automobile. A connector 51 is mounted to a proximal end of the cable 50 and a plug 52 is mounted to a distal end of the cable 50. The plug 52 plugs into the socket 41 and makes contact with the contact of the socket 41. The connector 51 connects with a cigarette lighter outlet of the automobile to allow DC electricity having an electrical power of up to 150-watts to flow from the cigarette lighter outlet through the cable 50 into the DC/AC adapter 40.
FIGS. 8 and 9 illustrate a conventional DC/AC adapter assembly 64 having the DC/AC adapter 40 and a cable 60. The cable 60 is used to connect the DC/AC adapter 40 with an automotive battery. Crocodile clips 61 are mounted to a proximal end of the cable 60 and a plug 62 is mounted to a distal end of the cable 60. The plug 62 plugs into the socket 41 and makes contact with the contact (not shown) of the socket 41. The crocodile clips 61 are connected to an automotive battery to allow DC electricity having an electrical power of 200-watts to flow from the battery through the cable 60 into the DC/AC adapter 40.
The DC/AC adapter 40 is configurable to receive input DC electricity having an electrical power of 150-watts through the cable 50 or input DC electricity having an electrical power of 200-watts through the cable 60. If the DC/AC adapter 40 is configured to receive 200-watts of electricity, the connector 51 of the cable 50 is connected to a cigarette lighter outlet, and the plug 52 of the cable 50 is plugged into the DC/AC adapter 40, the current flowing through the cable 50 into the DC/AC adapter 40 will overload the cable 50. As a result, the cable 50 may become damaged or users of the DC/AC adapter 40 may become injured.
In light of the above, a need exists for reducing the occurrence of power-overloading in a DC/AC adapter assembly.